Mass Changes When A Reactant Or Product Is A Gas (GCSE Chemistry)

Which method ensures the mass of a reacting system remains constant during a reaction that produces gas so students can easily demonstrate conservation of mass?

When 1.00 g of methane (CH4) is burned in an open system and CO2 escapes, what happens to the mass of the remaining solids/liquids?

2H2 + O2 ? 2H2O. If 3.50 dm3 of H2 is reacted completely at room temperature and pressure, how much air (volume in dm3) is needed if air contains 20% oxygen by volume?

A student wants to demonstrate conservation of mass for a reaction that produces CO2. Which setup will best show no mass change?

Which experimental change will make the measured mass decrease during a reaction more accurately reflect the mass of gas evolved rather than being underestimated?

When 1.00 g of carbon is completely oxidised to CO2 (oxygen supplied from air), by how much does the mass of the carbon sample increase? (Ar C = 12, O = 16)

24.0 cm3 of hydrogen is collected at room temperature and pressure in an open experiment where H2 escapes from the system. How many moles of H2 does this represent? (Use 24 dm3 = 24 000 cm3 per mole.)

A container initially contains 1.00 g of hydrated copper sulfate. After heating to drive off water the mass is 0.64 g. What mass of water was lost?

When a metal reacts with oxygen in a sealed container (no matter leaves), what happens to the total mass of the sealed container and contents?

If 2.00 g carbon burns to CO2 and all the oxygen comes from the air, what is the mass of the CO2 produced? (Ar C = 12, O = 16)

A student reacts 2.00 g of zinc with excess hydrochloric acid in an open flask (Zn ? Zn2+ + 2 e-; reaction produces H2 gas). Using Zn Ar = 65.4, how much mass is lost from the system when the reaction produces hydrogen gas? (Give an approximate value.)